Hydraulic power system



March 21, 1950 N. w. TAYLQR HYDRAULIC POWER SYSTEM Filed Appil 3, 1948 mR 3 0 T M MT N. :WN a v E H a u N Ul- W R .Il U F N T w m f w o up .o 17 mw .1 A 3 V W P I-l m \\lNv. m- H M M w Alm 0 .5f ll\\% (u al Z 3 )1 7EN \..V my A71 4 0 8 4 4 4 4 H m J 3 llll 4 l w l 4 Patented Mar. 21,1950 UNITED STATES PATENT OFFICE HYDRAULIC POWER SYSTEM Norman W.Taylor, Cleveland Heights, Ohio, as-

signor to The Warner & Swasey Company, Cleveland, Ohio, a corporation ofOhio Application April 3, 1948, Serial No. 18,809

7 Claims. 1

This invention relates to a hydraulic power system valve, andparticularly to a valve adapted to be employed in the hydraulicoperating circuit to a hydraulic motor which actuates a movable elementof an apparatus.v

The apparatus with which the valve embodying the invention can beadvantageously employed might be any type of apparatus wherein thehydraulic motor raises and lowers a movable element of the apparatus andwhich element is subject to different loads or forces at dilerent timesand particularly with respect to its lowering movement. As examples ofapparatus wherein the valve may be advantageously employed reference ismade without limitation to a hydraulic hoist, elevator, thehydraulically actuated pivoted boom of a derrick or of a materialhandling machine. Inasmuch as the valve may be employed with specialutility in the operating circuit of a hydraulic motor that actuates theraising and lowering of a pivoted boom, it will be described herein withparticular reference to such an environment. Especially is this the casewhere the weight of the load raised or lowered by the boom may bedifferent at diierent times and also where the application of the loadwith respect to the pivotal axis of the boom may change for differentoperations of the boom.

An object of the invention is to provide an improved and novel valve foruse in the operating circuit to a hydraulic motor that actuates theraising and lowering of a movable element of an apparatus and whichvalve ordinarily provides for a substantially constant predeterminedrate of lowering movement or travel of the element at all timesirrespective of the load acting on the element during the loweringmovement.

Another object is to provide i'n the operating circuit to the hydraulicmotor that actuates the raising and lowering of a movable element of anapparatus, a valve which ordinarily maintains during the loweringmovement of the element a substantially constant rate of discharge fromthe exhaust side of the motor, and should back pressure reacting on theexhaust side of the motor develop in the valve in excess of apredetermined pressure, said valve will function automatically andmomentarily to reduce from full line pressure the input pressure to themotor until the back pressure falls to or below said predeterminedpressure.

Another object is to provide a valve which can be used in the operatingcircuit to a hydraulic motor that raises and lowers an element of anapparatus and which valve automatically provides for a faster raisingoperation of the motor and raising movement of the element than thelowering operation and movement thereof and also provides for asubstantially constant speed lowering operation of the motor andlowering movement of the element, irrespective of the load applied tothe element during its lowering movement.

A further objectv of the invention is to provide in the hydraulicraising and lowering operation of a movable element of an apparatusmeans for maintaining a substantally uniform lowering rate of movementof the element irrespective of loads, thus providing for safety ofoperation.

Further and additional objects and advantages not hereinbefore referredto will become apparent during the description of an embodimnt of theinvention which is to follow.

Referring to the accompanying drawing;

Fig. 1 illustrates said embodiment of the invention and shows the valvediametrically located in the operating circuit to a hydraulic motor; thesection through the valve being taken substantially along line I-l ofFig. 2 and the two plunger valves in the valve being shown in theirnormal positions.

Fig. la is a sectional view of the valve shown in Fig. l but with thetwo valve plungers thereof moved automatically from their normalpositions and into the positions they may momentarily have duringlowering operation of the motor when the back pressure on the exhaustside of the motor exceeds a predetermined pressure and the line pressureon the input side of the motor is momentarily and automatically reducedsubstantially from full line pressure.

Fig. 2 is a sectional view taken substantially on line 2 2 of Fig. l,and

Fig. 3 is a sectional view taken substantially on line 3-3 of Fig. 2.

The valve embodying the invention is shown arranged in the operatingcircuit to a hydraulic motor l0 of the reciprocating piston type. Thepiston I l of the motor slides in the motor cylinder and actuatesthrough a piston rod I2 the raising and lowering of an element I3 of anapparatus. This element I 3 may be in the form of a.

pivoted boom that is raised and lowered at different times underdiierent load conditions. During raising operation of the motor l@ toraise the element i3 the piston Il moves upwardly in the motor cylinder,as viewed in the drawing, while during lowering operation of the motorto lower said element said piston moves downwardly in the motorcylinder. The motor cylinder is provided adjacent its opposite ends withports i4 and l5 to which are connected, respectively, hydraulic lines I6and l1 that extend to the valve of the invention.

The said valve comprises a valve housing I8 having therein adjacent itslower end, as viewed in the drawing, an L-shaped chamber i9 and adjacentits upper end a chamber 28. The chamber I9 is connected to the line I6and the chamber 25 is connected to the line l1. .The .valve housing i8also is provided with a chamber 2l. The chambers i9 and 2l of the valvehousing-are'connected by lines 22 and 23, respectively, to any suitableform oi selector valve for selecting 'the direction of operation of themotor.

In Fig. l, and for purposes of illustration only, the line 22 is shown`asconnected .to .a .port 24 .and the line23 to aport 25 `formed in thehousing 26 of aselect-or valve and communicating with theinterior .ofsaid housing. The selector valve has rockably mounted `therein adiametrically eX- tending valve vbody '21 which is ,provided with athrough ,passage 28 in communication at its midpoint with .a supply.line ,29 extending from a suitable source .of ,supply .of hydraulic-pressure medium. The valve .body 21 may be .rocked by ahandle 13G to .aposition wherein the through passage 28 in lthe valve body is incommunication with the .port .24 and out of .communication with the port.25 jf-orlowering operation .of the hydraulic motor or to a positionwherein said through passage communicates with the port `and .is out ofcommunication .with the portj24 for raising operation of the hydraulic.mot-or. The interior of the valve 'housing .is .connected by a port 3lto an .exhaustfline Sla which functions for Vboth 4of the operative.positonso'f the valve body just referred to. Also the valve body .mightbe moved to a third or idle position wherein the `passage 2% is .incommunication with 'the exhaust port 3l `while'both ports T24 .and 25.are out of communica- `tion with .either the inlet or exhaust sides ofthe valve.

.The valve'housing L8 adjacent .to the chamber .2li is shown .as-provided `withva through passage closed at its opposite ends bythreaded plugs 32 .and .S3 and forminga chamber .34 for a plunger valve.35 that is provided with .three land .portions 38, y3l .and .38., whichare slidable in said plunger valve chamber. A spring 39. of prede.termined .strength `is mounted in a central recess of the plug .3.3 andbears against the right hand Y.end of the plunger valve as viewed inFig. 1

,and acts .to maintain said plunger valve normally in the .position.shown -in Fig. l. The vplunger valve chamber 34 `in 4the normalposition of the `v`plunger valve 35 .is in .communication by means of aport 4i! with the chamber 20. The plunger lvalve chamber 34 -also when.the plunger valve is in its normal position is in communication bymeans of .a .port 4i with .a chamber 42. The chamber 42 is connectedalso to the left hand end .of the .plunger valve chamber .34, as viewedin the drawing bya small passage 43 which extends to .the left `side ofthe iland `3.6 of the plunger valve when said valve 'is .in its normalposition.

. The chamber 42 is also .connected by a port 44 to the chamber 2l, theeffective area of the port 44 being controlled by the tapered end of aneedle valve 45 having a threaded stem portion that is adjustablyscrewed in a threaded opening in the valve housing I8 and which portionprojects outwardly of said housing. It will be understood that theneedle valve 45, depending upon its particular adjusted position,controls the effective area of the port 44 and provides an adjustableorifice connection between the chambers 42 and 2i. The needle valve 45may be locked in adjusted position by means .of a threaded cap 46screwed onto the projecting threaded end of the needle valve.

The valve housing i8 is provided intermediate the chambers i9 and 2lwith a circular recess extending into the body from one side thereof and.forming ya chamber 41 for a plunger valve 48 that .is provided withspaced lands 49 and 5U slidable Yin the .chamber 41. The open end of therecess or chamber 41 is closed by a threaded plug 5i which vmounts aspring 52 of predetermined strength corresponding to the strength ofspring 39 and which spring 52 bears against the right hand. end of theplunger valve 48 and normally maintains rsaid valve in :the positionshown in Fig. l. The recess or ,plunger valve chamber 41 at its lefthand end is 'connected by a port 53 to the chamber 42. The ,plungervalve chamber 41 is connected to .the chamber 2l by a port 54 Awhich inthe normal position of the plunger valve d3 is closed by the land'5. Theplunger or valve chamber 4l is also connected by 'a third port 55 withthe chamber i9 and said port 55 is located at .all times ,intermediatethe lands 49 and 56.

' The valve housing 18 intermediate the cham- `hers 2li and?! isprovided with a'bore 5E closed at its right hand end, vasviewednFigBI bya plug 51 screwed into thevalve housing. The bore 56 adjacent its lefthand end, as viewed in Fig. 3, has a valve seat 58, it being noted thatthe left hand `end of the 'bore' 55 communicates through the valve seatwith the chamberf'l. The bore 5E .adjacent the valve seat 58communicates by a port .'59 with vthe chamber 2), while said bore56adjacen't its right 'hand end is also in communication with the chamber2l] by ra Yport 5U. A valve 'Bl is slidable in the `bore 5.6 and is heldseated on the seat 5S by a relatively weak spring 62, one end of which-abuts the valve Bl and the other end oi which extends into a `recessformed in the plug 5l.

.The operation of thevalve heretofore described .will now be explained.It will lbe .assumed that 1 hydraulic lpressure is Aon the vthroughpassage 218 of the selector valve .body .21 .and that said body is .inthe .position shown in ZFig. l and .that the hydraulic motor lll isoperating in .the lowering direction. It will .further be `assumed thatthe needle valve 45 .has been adjusted to the desired adjustment and.that the plunger valves 35 and .4.8 are .in their normal positions asindicated in Fig. l. At this time iull line pressure is flowing fromtheselector valve 26 .through line .22, chamber l, line l5 and port I4to the upper side of ythe piston l-i of the hydraulic motor. Thehydraulic medium below the :piston il is being yexhausted ythrough portl5. line I1 and into chamber 25. The hydraulic medium in .chamber 2c.acts Athrough port .69 -in conjunction with spring -52 to maintain thevalve .6l on its seat 53 and thus to vinterrupt Ycommunication betweenthe chamber 2l and chamber 2D by way .of the bore 56. However, since.the chamber .2D .communicates with the plunger valve chamber 34 thehydraulic Vmedium beneath the piston II will be exhausted through thechamber 20, port 40 and pass between the lands 36 and 3`| of the plungervalve 35 into the chamber 42. The exhausting hydraulic medium will thenpass from the chamber 42, through the needle valve controlled port 44into the chamber 2|. It will be recalled that the needle valve controlsthe effective area of the port 44, and hence controls the rate of iiowof the hydraulic medium through the port 44. The hydraulic mediumexhausted to the chamber 2| then flows through line 23, port 25 to theinterior of the selector valve and thence to the discharge line 3|a. Ifthe action of the full line pressure on the upper side of the piston Il,in conjunction with the load of the element I3 acting on the piston,tends to cause the piston to move in a lowering direction at a rate thatwill cause the hydraulic medium to exhaust into the chamber 42 fasterthan it can be exhausted therefrom to the chamber 2l through the needlevalve controlled port 44, then back pressure will be created in thechamber 42 and such back pressure acting through the passage 43 on theleft-hand end Aof the plunger valve 34 will overcome, when it reaches apredetermined pressure, the action of the spring 39 and shift theplunger valve 35 toward the right from the position shown in Fig. 1 tothe position shown in Fig. la, wherein the land 36 of the plunger valve35 closes the ports 4U and 4| and interrupts the exhaust of thehydraulic medium from the chamber '20. This back pressure that may bebuilt up in chamber 42 also acts simultaneously through port 53 to shiftplunger valve 48 against the predetermined resstance of the spring 52from the position shown in Fig. l and into the position shown in Fig. lato move land 50 of said plunger valve to the right of port 54 and thusplace the chamber 2| in communication with the chamber I9 through theports 54 and 55 and the plunger valve chamber 41. Consequently theincoming line pressure is Icy-passed from chamber I9 to chamber 2| andthence to exhaust to reduce the pressure acting on the upper side of thepiston I I and thus to decrease the rate of lowering movement of thepiston I and the element I3.

Theoretically the hydraulic medium below the piston I I under theconditions just referred to is trapped and the downward movement of thepiston would cease. However, this condition is a momentary one, since assoon as the land 36 of the plunger valve 35 has moved to the positionshown in Fig. la, the pressure f the hydraulic medium in chamber 42quickly falls to a point where the spring 39 shifts the plunger valve toits normal position of Fig. 1. Also at this time the spring 52 functionsto shift the plunger valve 48 from the position of Fig. la to its normalposition Vof Fig. 1. Therefore the chamber 2U after being momentarilyclosed from communication with the chamber 42 is again in communicationtherewith while the chamber i9 after being momentarily in communicationwith the chamber 2| is again out of communication therewith and fullline pressure is flowing to the upper side of the piston.

It will be understood that during the lowering operation of the motorthe pressure in chamber 42 is maintained substantially constant sincethe discharge area for the hydraulic medium in said chamber 42 is of apredetermined size by the 'adjustment of the needle valve, therebyallowing the medium to flow from the chamber 42 to the chamber 2| at asubstantially uniform rate.

Consequently'the 'lowering movement of the pis'- t'on of the motor I0 issubstantially at a uniform predetermined rate, irrespective of the loadimposed on the piston duringsuch lowering movement. I

When it is desired to loperate the motor l0 in the raising direction theselector valve body 21 is placed in registry with the port 25, whereuponline pressure flows through the' line 23 and into the chamber 2|. Anegligible portion of this pressure will flow from the chamber 2|through the port 44 around the needle valve, through chamber 42, ports4| and Minto the chamber 2B. However, the hydraulic pressure medium inchamber 2l acting on valve `II will overcome the weak spring 62 andunseat said valve and hence the major portion of the medium` followingthe line of least resistance will flow from the chamber 2| through theport '59 directly into the chamber 2|! from whence it flows through lineIl to the underside yof the piston ll. At this time the cylinder of themotor above the piston is being exhausted through line liychamber I9,line 22, and through the selector valve to discharge. At all timesduring the raising operation of the motor the plunger valves 35 and 48remain in their normal positions as shown in Fig. 1. The raisingmovement being effected at full line pressure is more rapid than thesubstantially uniform lowering movement of the piston of the hydraulicmotor and consequently the element actuated by the motor is raised morerapidly than it is lowered.

The term chamber as used herein to designate the yenclosed spaces I9,25, 2|, 34, 42 and 41 in the housing I8 is intended to include anyenclosed space such as a bore, a compartment, a passage, a cavity or theequivalent. For convenience and to render the claims more readilyunderstandable the chambers I9, 2|), 2| and 42 will be referred toin'the claims, respectively, as through passage, ow chamber, cavity andpressure chamber. Although valves 35 and 4B have been shown anddescribed as plunger valves, it will be understood that various otherform of valves subject to the pressure in pressure chambei' 42 might beemployed in their place and stead to accomplish the same purposes as dosaid plunger valves'.

Although a preferred embodiment of the invention has been illustratedand described herein it will be understood that the invention issusceptible of various modifications and adaptations within the scope ofthe appended claims.

Having thus described my invention I claim:

1. In a hydraulic power system, in combination, a hydraulic motor for'eiecting the raising and lowering of .a movable element of an apparatusand including a cylinder and a piston movable therein, a hydrauliccircuit adapted to be connected to a'source of hydraulic pressure andincluding a direction selector valve and a hydraulic control valve insaid circuit intermediate said selector valve and said motor, saidcontrol valve comprising a housing having therein a ow chamber and athrough passage, said chamber and said passage being connectedrespectively by said circuit to said motor on opposite sides of thepiston thereof, said passage being connected by said circuit to saidselector valve, a cavity in said housing and connected by said circuitto said selector valve, a pressure chamber in said housing, means inAsaid housing providing communication between said pressure chamber andsaid ow chamber, pressure actuated valve means operatively 7l associatedwith said last means for controlling communication between lsaidchambers and normally held .in open position by a predetermined force.and subject to the pressure .in saidpres'sure chamber to be movedthereby when said pressure exceeds said force to diminish thecommunication between said chambers, :means placing said pressurechamber and said cavity .in communication, a valve controllingv theeffective area of said communication between said pressure chamber andsaid cavity, means placing said passage and said cavity communication,and a pressure actuated valve operatively associated with said lastmeans and normally .held in closed position by a predetermined force andsubject to the pressure in `said pressure chamber to be moved therebywhen `said pressure vexceeds said -forceto establish communicationbetween said passage and said cavi-ty.

v2. A hydraulic power system as dened iii-claim i Iand wherein saidhousing is provided witha bore closed at its outer end and having itsinner end communicating with said cavi-ty., said .bore being providedwith a valve seat adjacent its inner end, means located intermediate theinner and outer ends of said bore and placing said bore in'communication with said vflow chamber, a valve in said bore, and meansmaintaining said iatter valve against said 'seat with a predeterminedpress-ure whereby when said cavity is 'subiect to f-ull line pressure'said valve in said bore is unseated and the incoming hydraulic pressureis icy-passed from said 'cavity through said bore to said -ilow chamberfrom whence it passes to said motor.

3. In a hydraulic power system, in combination, a hydraulic motor toreffecting the raising and lowering of a movable element of an apparatusand including a cylinder and a piston movable therein, a hydraulic'circuit connected to said motor and adapted to be connected to a sourceof supply of hydraulic pressure and includ-ing a direction selectorvalve and a hydraulic control valve located intermediate said motor andsaid selector valve, said control valve comprising a housing havingtherei-nja il'ow chamber connected through said circuit to said motor onone side of the piston while 'said moto-r on the opposite side of thepiston is connected through said circuit to said selector valve, acavity in said housing and connected through sai-d circuit to saidselector valve, a plunger valve chamber in said housing, means placingsaid plunger valve chamber in communication with. said flow chamber, apressure chamber in said housing, means placing said pressure chamber incommunication with said valve chamber intermediate the ends thereof andwith said cavity, a valve controlling the eiective area of communicationbetween said pressure chamber and said cavity, a plunger valve mountedin said valve chamber and normally maintained by a predetermined forcein a position wherein communication exists between said valve chamberand said now and pressure chambers, and additional means providingcommunication be tween said pressure chamber and an end of said valvechamber whereby whenever pressure builds up in said pressure chamberexceeding said pre determined force said plunger valve is shiftedcausing reduction of communication between said flow and pressurechambers.

4. A hydraulic power system as defined in claim 3 and wherein saidhousing is provided with a bore closed at its outer end and having itsinner end communicating with said cavity, sa.id bore being provided witha valve seat adjacent its ine ner end, means located intermediatetheinnerand outer ends of said bore and placing said bore ihcommunication with Isaid Ilcw chamber, a valve Ain said bore, andmean-sv maintaining `said valve against said seat with a predeterminedpressure whereby when 'said cavity is subject to full line pressure saidvalve -in vv'said bore is unseated and the incoming hydraulic `pressuremedium is bypassed through said bore from said cavity to said flow'chamber rom whence it passes to said one side of the .motor piston.

`5f. In ahydraulicpower system, :in combination, a hydraulic motor foreffecting Athe raising and lowering fof a movable element vof anappara-tus and :including :a cylinder `and a piston, a hydraulic circuitconnected to vsaid motor 'and adapted to be connected to a source ofsupply of hydraulic pressure and including a direc-tion selector valveand a hydraulic control valve located intermediate said motor and saidselector valve, said control valvecomprisin'g a housing having therein aflow 'chamber Vand Ia thorough passage, said flow chamber and saidpassage being connected respectively to said motor through said circuiton opposite sides of said piston, said passage being connected throughsaid circuit to 'said selector valve, a cavity in said housing andconnected through said circuit to said selector valve, a plunger valvechamloer in said housing, means placing said plunger valve chamber incommunication with said flow chamber, a second Iplunger valve chamber insaid housing, means placing said second plunger valve chamber incommunication with said passage and said cavity, a pressure chamber insaid housing, means placing said Vpressure chamber in communi'cationwith said irst plunger valve chamber intermediate rthe ends thereof andwith said second .plunger valve chamber adjacent an end thereof and withsaid cavity, a valve controlling the 1effective area of communicationbetween said pressure cham-ber and said cavity, plunger valves mountedin 4said plunger valve chambers and normally maintained by apredetermined force in positions wherein communication exists betweensaid iirst plunger valve chamber and said flow and pressure chambers andis interrupted between said second plunger valve chamber and saidcavity, and additional means providing communication between saidpressure chamber and an end of said iirst plunger valve chamber wherebywhenever pressure builds up in said pressure chamber exceeding saidpredetermined force both of said plunger valves are shifted causinginterruption of 'communication between said iiow and pressure chambersand placing said passage and said cavity in communication through saidsecond plunger valve chamber.

6. A hydraulic power system as defined in claim 5 and wherein saidhousing is provided with a bore closed at its outer end and having itsinner endV communicating with said cavity, said bore being provided witha valve seat adjacent its in# ner end, means located intermediate theinner and outer ends of said bore and placing said bore in communicationwith said iow chamber, a valve in said bore, and means maintaining saidlatter valve against said seat with a predetermined pressure wherebywhen said cavity is subject to `full line pressure said valve in saidbore is unseated and the incoming hydraulic pressure medium is byepassedthrough said bore from said cavity to said now chamber from whence itpasses to said motor.

'L Ahydraulic power system as dened in claim and wherein said valve thatcontrols the et` iective area of communication between said pressurechamber and said cavity is an adjustable Number valve having provisionfor manually seating the 1,923,595 same in different adjusted positionsto vary the 2,166,940 said eiective area, of communication. 2,272,684

NORMAN W. TAYLOR. 5

REFERENCES CITED Number The following references are of record in the7751261 le of this patent:

Name Date Temple Aug. 22, 1933 Conradson July 25, 1939 Vickers Feb. 10,1942 FOREIGN PATENTS Country Date France Oct. 8, 1934

